1. Technical Field
The present invention is directed toward a running board for use with a motor vehicle, and more particularly toward an improved running board construction utilizing a combination of molded plastic and steel components.
2. Background Art
Conventional vehicles of the sport utility, pick-up truck, and van types frequently have running boards to facilitate entry and exit therefrom. Because of the often appreciable height differential between the cabs or passenger compartments of such vehicles and the ground level, running boards are mounted alongside vehicle frame below the door openings to provide a convenient step for individuals attempting to enter and leave the vehicle.
In order to support the weight of vehicle occupants standing on a running board, running boards are commonly formed of metal or wood and are rigidly secured to the vehicle frame. That is, structural rigidity is an important consideration in the selection of materials for running board construction. Although the use of such materials is reasonably effective to withstand the repeated loadings associated with frequent entry into and exit from vehicles, a number of significant problems exist.
During operation of a vehicle, running boards are continuously exposed to the rather abusive outdoor environment. Consequently, the running board step surface tends to accumulate rain water, ice, snow, mud, and various other materials. Because of the relatively low coefficients of friction of the above noted running board materials selected primarily on the basis of structure rigidity, the running boards can become slippery and footing is substantially degraded.
Running boards also enhance the aesthetic appearance of the vehicle. Commonly, a running board has highly polished chrome or colored surfaces which are coordinated with the vehicle body panels. Due to the repeated foot traffic to which a running board is subjected, however, the surfaces can become scuffed and the paint can be scratched and chipped.
An additional aesthetically pleasing feature of running boards is a smooth blending of the running board ends into the vehicle body contour. Typically, the end edges of the running board are rounded and blended integrally into the vehicle body, with the running board ends abutted against the vehicle and secured by means of rigid clamps.
Because of the rigid connection between the running board ends and the vehicle body, significant stresses can occur in the vehicle body when the running board is subjected to thermal loading. That is, fluctuations in temperature cause expansion and contraction of the running board components. As the different components change size at different rates, the running board ends are force against or, alternatively, pulled away from the vehicle body. The rigid connection restricts the relative displacement of the running board ends and instead applies forces to the vehicle body.
The present invention is directed toward overcoming one or more of the problems set forth above.